Effects of Vitamin D3 Treatment on Polycystic Ovary Symptoms: A Prospective Double-Blind Two-Phase Randomized Controlled Clinical Trial

Background/Objectives: Vitamin D deficiency is common in women with polycystic ovary syndrome (PCOS) and may be associated with metabolic and endocrine disorders as well as ovulatory dysfunction. Vitamin D supplementation may improve ovarian dysfunction and follicular development by effecting gene expression. The aim of the present study was to investigate the effects of vitamin D supplementation in women with PCOS through a prospective, randomized, two-phase, parallel design, placebo-controlled trial. Methods: We assessed the impact on ovarian morphology, cycle length, and ovulatory dysfunction. Transvaginal ultrasonography (TVUS) examinations and clinical laboratory assessments were conducted at the baseline, and again after 12 and 24 weeks. The participants received vitamin D (30,000 IU/week) or a placebo (without concurrent metformin use) for 12 weeks, supplemented with calcium, followed by an additional 12 weeks of vitamin D treatment. Results: The treatment resulted in improvements in ovarian morphology and regularity of menstrual cycles in more than half of the patients. Additionally, vitamin D3 was associated with a significant increase in the ovulation rate. A statistically significant reduction in mean testosterone levels was observed in the subgroup of patients with an LH/FSH ratio greater than 2. Conclusions: Our results suggest that vitamin D3 treatment could function as either a standalone or an adjunctive therapy in the management of PCOS.